Most low-cost CMOS image sensors use a rolling shutter, in which successive rows of sensor elements are triggered sequentially to capture light. This method of image acquisition thus records each individual frame not as a single snapshot at a point in time, but rather as a sequence of image stripes scanning across the frame. The result of the rolling shutter is that not all parts of the optical image are recorded at exactly the same time (although the frame is stored as a single electronic image).
The use of a rolling shutter introduces a temporal shear in the image frame, which can create artifacts in imaging of moving objects. Bradley et al. address this problem in “Synchronization and Rolling Shutter Compensation for Consumer Video Camera Arrays,” IEEE International Workshop on Projector-Camera Systems—PROCAMS 2009 (Miami Beach, Fla., 2009), which is incorporated herein by reference. The authors propose to solve the problem using synchronized stroboscopic illumination.